In the case of computer clouds or cloud computing, services and data are relocated and are available via the Internet or an intranet. In such a case, the user thus needs to have a network connection in order to be able to use a cloud application. In certain application scenarios, such as in the automotive or mobile sector, for example, users typically do not have a permanent, uninterrupted connection to the Internet, however. Further, in the case of automation systems, for example, there are high demands on availability and there is the desire for such systems to be intended to continue to operate autonomously even without a connection to a network.
In general, it is known practice to provide redundant network connections, e.g. multiple cables or a landline network connection and a mobile radio connection. In the event of failure of one network, it is thus possible to use the second network to communicate.
Further, it is known practice to provide redundant servers in a computer center, so that a redundant substitute server can undertake service provision in the event of failure of a server. High-availability solutions of this kind are complex, however, and therefore expensive and not available generally in the case of cloud services.
In Shi et al. Computing in Cirrus Clouds: The Challenge of Intermittent Connectivity. In Proceedings of MCC 2012. ACM. 2012, applications are normally executed locally on the terminal and, on connection to a cloud, these applications can be relocated to the cloud as required.
In the case of the cloud-based application “Google Docs” it is possible to configure an offline mode, see https://support.google.com/drive/answer/1628467?hl=de. In this context, activation is possible such that documents are processable locally even without a network connection, with the documents stored offline then being synchronized when a network connection is available.